V-shaped belt



c. w. YELM Jan. 15, 1935.

V-SHAPED BELT Filed April 2, 1934 III! Patented Jan. 15, 1935 I UNITEDSTATES .PATENT OFFICE 1,988,292 V- SHAPED BELT Charles W. Yelm, Denver,Colo., assignor to The Gates Rubber Company, Denver, 0010., acorporation of Colorado Application April 2, 1934, Serial No. 718,603 6Claims. (Cl. 74-233) This invention relates to improvements in beltsFig. 2 is a section taken on line 2-2, Fig. 1; for the transmission ofpower and has reference Fig. 3 is a transverse section through the beltmore particularly to side driving belts of the and a pulley showing therelative position of the type usually referred to as V-shaped belts. twoparts; and

Where V-shaped belts are employed for the Fig. 4 is a diagram showingthe change that 6 transmission of power they are usually made of takesplace in the cross section of the belt when comparatively small crosssectional areas and it is subjected to strains during operation.

a number of belts employed in parallel, because The belt that forms thesubject of this inby this. means the belts can be made smaller andvention is preferably composed of a number of will be subjected to lessstrains than if the layers 5 of rubberized cord. In the drawing 5 l0entire power was transmitted through a single layers of cord have beenshown, but a greater belt. or less number may be employed as occasionmay It is sometimes desirable and necessary .to arise. Located on theinside of the cord layers transmit by a single V-shaped belt a much is aplurality of layers 6 of rubberized fabric.

16 larger amount of power than is usually so trans- This fabric maybebias cut or straight out, as mitted and this is especially true where aspeed may be desired, on the inside of the fabric layers changingmechanism is interposed between the a body '7 of rubber composition ispreferably proprime mover and the machine. In one type of vided. Atension arch 8 extends transversely of speed change mechanism twoV-shaped pulleys the belt and is formed from one or more layers areemployed, the sides of the grooves of which of rubberized cords whoseupper ends extend 20 can be moved towards and away from each other overthe outer edges of the outer cord layer 5 so as to automatically changethe speed ratio as indicated by reference numeral 9. Secured to and thebelt that forms the subject of this inthe outside of the tension archare strips 10 of vention is intended more particularly for userubberized fabric and enclosing the driving sides a with such speedchange apparatus, although it 11 and the inside 12 of the belt is alayer of can, of course, be employed in connection with bias cutrubberized fabric. The outer covering ordinary V-type transmissions.fabric does not extend over the top but prefer- In a copendingapplication Serial No. 706,495 ably terminates at the point indicated byreferilled January 13, 1934, a belt of the type disence numeral 13. Whena belt of the shape :0 closed in this application has been shown andshown in Fig. 2 is in place in the groove of a described. The belt thatforms the subject of pulley having inclined sides, the belt and the theapplication above identified is provided with pulley form an assemblylike than shown in means for preventing or resisting transverse Fig. 3.The pulley indicated in Fig. 3 is preferfiexure of the belt. ablyprovided with two relatively movable parts This invention differs fromthe one described 14 whose inner or adjacent surfaces 15 are out- 35 andclaimed in the application above identified wardly inclined so as toform friction surfaces primarily in this, that in addition to the meansagainst which the inclined sides 11 of the belt for resisting transverseflexure means is also rest. In practice the surfaces 15 are slightlyprovided for automatically maintaining the disconvex so as to take careof variations in shape 0 tance between the outer corners of the beltwhen the radius of curvature of the belt is substantially constant whenit is flexed transchanged. versely due to the strains to which it issub- When the belt isinplace in the pulley as shown jected duringoperation. By the expression in Fig. 3 and subjected to tenslonalstrains the transverse flexure is meant a bending inwardly resultant ofthese strains can be supposed to be 5 of the belt by force from theoutside towards the centered at point 16 and actsin the directioninside, flexure would change the straight inner of the arrow 1'7. Suchstrains tend to fiex the surface of the belt into a convex surface. belttransversely. Such flexure is resisted by In order to more clearlydescribe this inventhe tension arch 8 but since the belt is made tion,reference will now be had to the accomfrom rubberized fibrous materialand rubber 5o panying drawing in which the preferred concomposition, itwill yield and assume a shape struction has been illustrated, and inwhich: somewhat like that indicated in dot and dash Fig. 1 is a sideelevation of the belt looking lines in Fig. 4. If no means is providedto exin the direction of arrow 1, in Fig. 2, a portion pand thetransverse dimension of the belt near of the belt having been brokenaway to better its outer surface, the outer comers, which have udisclose the construction; been designated by reference numerals 18 inFig. 4, will move inwardly and if this occurs the pressure of the sides11 will decrease from.the inner corners 19 to the outer comers 18 andthis variation in pressure would be highly undesirable. To prevent theinclination of the vsides of the belt from changing to any appreciableextent when transversely flexed, the layers 5 of cord and the layers 6of rubberized fabric have been bowed outwardly so as to form arches thattend to move the corners 18 outwardly when these arches arestraightened. By properly arching the materials in layers 5 and 8, it ispossible to produce a belt that will not change the inclination of thesides 11 when it is transversely flexed.

It is also well known that when any extensible material is subjected totensional strains, there is a tendency to decrease the cross sectionalarea and change the shape of the cross section in ways depending uponthe original shape. This effect is known as the Poisson effect and withbelts of this type, there is a tendency to decrease the distance betweenthe outer corners when tension is applied, even if there is notransverse fiexure. Such deformation due to tension alone will, however,tend to flatten the arches 5 and 6 and the expansion that will be causedthereby will neutralize the contraction that would otherwise take placeso that the inclination of the sides 11 will remain the same, even ifconsiderable tension is applied to the belt.

It will be seen from the above description that the belt that forms thesubject of this invention is so constructed that the inclination of thesides 11 will be retained substantially constant at varying loadsbetween reasonable limits and that this property is attained by theemployment of a tension arch 8 and compression arches 5 and 6. It is, ofcourse, possible to dispense with the rubberized fabric layers 6 inwhich case the rubberized cord layers 5 would be the compression arch.

In a wide V-shaped belt of the type to which this belongs and which isconstructed with a flat layer or layers of cord, the tension in thecords adjacent the center will diminish when the belt is flexedtransversely and the strains will be transferred to the cords nearer theedges, thereby producing a variable distribution of tensional strainsthat tend to break down the cords near the edges sooner than if thestrains were uniformly distributed.

In the present construction the transverse flexure is resisted by thetension and the compression arches, as above explained, and this servesto maintain a more uniform distribution of tension in the cords with aresult that the belts last longer and give better service than similarbelts that do not have the compression arch feature.

Although the inverted suspension arch 8 is desirable, goodeifects can beobtained without this element as the straightening of the compressionarches will tend to keep the pressure between the sides 11 and 12 equalat all times, but the tension arch is considered to be a useful elementin this combination and is very effective for the purpose of preventingtransverse flexure.

Having described the invention what is claimed as new is:

1. A power transmission belt of the side driving V-shaped type and ofgreater width than thickness, the body of the belt comprising a layer ofcord extending in the direction of the length of the belt and locatednear the outer surface thereof to resist tension, said layer beingcontinuously curved outwardly when viewed in a plane transverse to thebelt, a center of double convex cross section located on the inside ofthe cord layer and a layer of cord fabric extending transversely of thebelt and resting against the convex inner surface of the center, theends of the cords terminating near the outer corners of the belt, thebelt being moulded into the shape desired.

2. A power transmission belt of the side driving V-shaped type and ofgreater width than thickness, the body of the belt comprising a layer ofcord extending in the direction of the length of the belt and locatednear the outer surface thereof to resist tension, said layer beingcontinuously curved outwardly when viewed in a plane transverse to thebelt, a center of double convex cross section located on the inside ofthe cord layer, a layer of cord fabric extending transversely of thebelt and resting against the convex inner surface of the center, theends of the cords terminating near the outer corners of the belt, thebelt being moulded into the shape desired, and a fabric covering for theinner surface and the inclined driving surfaces of the belt.

3. A power transmission belt of greater width than thickness of the sidedriving V-shaped type, said belt comprising an elongated inner body ofreadily deformable material whose transverse cross section is convexoconvex, a layer of substantially parallel cords located on the outsideof said body with the cords extending in the direction of its length, alayer of cords ex-' tending transversely of the body and lying along itsinner convex surface, the ends of the last named cord layer terminatingadjacent the outer corners of the belt.

4. A power transmission belt of the side-driving V-shaped type and ofgreater width than thickness, the belt having a layer of longitudinallyextending cords whose transverse section is a continuously curvedoutwardly bowed arch and which constitutes a means for maintaining thedistance between the outer corners of the belt substantially constantwhen it is bent inwardly, an inverted tension arch formed from a layerof transversely extending cords continu-- ously curved inwardly andembedded in the material of the belt and which resists forces tending tobend the belt inwardly, the space between the concave inner surface ofthe longitudinally extending cord layer and the concave surface of thelayer of transversely extending cords, which form a tension arch, havinga filling of readily deformable material comprising a rubbercomposition.

5. A power transmission belt of the side driving V-shaped type and ofgreater width than thickness composed of rubber composition andrubberized fibrous material, the belt having a layer of cord embeddedtherein and extending across the belt from between the outer cornersthereof, the layer being continuously bowed towards the inside of thebelt to form a tension arch, and a layer of longitudinally extendingcords adjacent the outer surface of the belt for resisting longitudinalstresses, the inner surface of the last named cord layer beingtransversely concave, a filling of readily deformable materialcomprising rubber composition between the two cord layers, the outersurface of the belt of cord extending transversely of the belt from theouter corners, the transversely extending cords being on the inside ofthe cord and fabric assembly, and rubberized fabric and rubbercomposition on the inside of the transverse cord, the belt being mouldedinto the shape desired and the driving sides and the inside covered withbias cut rubberized fabric.

CHARLES W. YELM.

